====================================================== WARNING: possible circular locking dependency detected 4.14.155-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor.1/27284 is trying to acquire lock: (pmus_lock){+.+.}, at: [<000000005e171d06>] swevent_hlist_get kernel/events/core.c:7917 [inline] (pmus_lock){+.+.}, at: [<000000005e171d06>] perf_swevent_init+0x123/0x4f0 kernel/events/core.c:7977 but task is already holding lock: (&cpuctx_mutex/1){+.+.}, at: [<00000000ca0f2e98>] perf_event_ctx_lock_nested+0x15a/0x2d0 kernel/events/core.c:1241 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&cpuctx_mutex/1){+.+.}: __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0xf7/0x13e0 kernel/locking/mutex.c:893 mutex_lock_double kernel/events/core.c:9939 [inline] __perf_event_ctx_lock_double kernel/events/core.c:9998 [inline] SYSC_perf_event_open kernel/events/core.c:10263 [inline] SyS_perf_event_open+0x12cf/0x2560 kernel/events/core.c:10018 rtc_cmos 00:00: Alarms can be up to one day in the future do_syscall_64+0x19b/0x520 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 -> #1 (&cpuctx_mutex){+.+.}: __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0xf7/0x13e0 kernel/locking/mutex.c:893 perf_event_init_cpu+0xa8/0x150 kernel/events/core.c:11261 perf_event_init+0x289/0x2c5 kernel/events/core.c:11308 start_kernel+0x583/0x890 init/main.c:645 secondary_startup_64+0xa5/0xb0 arch/x86/kernel/head_64.S:240 rtc_cmos 00:00: Alarms can be up to one day in the future -> #0 (pmus_lock){+.+.}: lock_acquire+0x12b/0x360 kernel/locking/lockdep.c:3994 __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0xf7/0x13e0 kernel/locking/mutex.c:893 swevent_hlist_get kernel/events/core.c:7917 [inline] perf_swevent_init+0x123/0x4f0 kernel/events/core.c:7977 perf_try_init_event+0xe5/0x200 kernel/events/core.c:9363 perf_init_event kernel/events/core.c:9401 [inline] perf_event_alloc.part.0+0xd1e/0x21d0 kernel/events/core.c:9661 perf_event_alloc kernel/events/core.c:10028 [inline] SYSC_perf_event_open kernel/events/core.c:10135 [inline] SyS_perf_event_open+0x6eb/0x2560 kernel/events/core.c:10018 do_syscall_64+0x19b/0x520 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 other info that might help us debug this: Chain exists of: pmus_lock --> &cpuctx_mutex --> &cpuctx_mutex/1 rtc_cmos 00:00: Alarms can be up to one day in the future Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&cpuctx_mutex/1); lock(&cpuctx_mutex); lock(&cpuctx_mutex/1); lock(pmus_lock); *** DEADLOCK *** 2 locks held by syz-executor.1/27284: #0: (&pmus_srcu){....}, at: [<0000000055dd9ff2>] perf_event_alloc.part.0+0xb39/0x21d0 kernel/events/core.c:9655 #1: (&cpuctx_mutex/1){+.+.}, at: [<00000000ca0f2e98>] perf_event_ctx_lock_nested+0x15a/0x2d0 kernel/events/core.c:1241 stack backtrace: CPU: 1 PID: 27284 Comm: syz-executor.1 Not tainted 4.14.155-syzkaller #0 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0xe5/0x154 lib/dump_stack.c:58 print_circular_bug.isra.0.cold+0x2dc/0x425 kernel/locking/lockdep.c:1258 check_prev_add kernel/locking/lockdep.c:1901 [inline] check_prevs_add kernel/locking/lockdep.c:2018 [inline] validate_chain kernel/locking/lockdep.c:2460 [inline] __lock_acquire+0x2f5f/0x4320 kernel/locking/lockdep.c:3487 lock_acquire+0x12b/0x360 kernel/locking/lockdep.c:3994 __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0xf7/0x13e0 kernel/locking/mutex.c:893 swevent_hlist_get kernel/events/core.c:7917 [inline] perf_swevent_init+0x123/0x4f0 kernel/events/core.c:7977 rtc_cmos 00:00: Alarms can be up to one day in the future perf_try_init_event+0xe5/0x200 kernel/events/core.c:9363 perf_init_event kernel/events/core.c:9401 [inline] perf_event_alloc.part.0+0xd1e/0x21d0 kernel/events/core.c:9661 perf_event_alloc kernel/events/core.c:10028 [inline] SYSC_perf_event_open kernel/events/core.c:10135 [inline] SyS_perf_event_open+0x6eb/0x2560 kernel/events/core.c:10018 do_syscall_64+0x19b/0x520 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x45a639 RSP: 002b:00007f4eed79bc78 EFLAGS: 00000246 ORIG_RAX: 000000000000012a RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 000000000045a639 RDX: 0000000000000000 RSI: ffffffffffffffff RDI: 0000000020000200 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000003 R11: 0000000000000246 R12: 00007f4eed79c6d4 R13: 00000000004c7b91 R14: 00000000004ddb70 R15: 00000000ffffffff device nr0 entered promiscuous mode rtc_cmos 00:00: Alarms can be up to one day in the future rtc_cmos 00:00: Alarms can be up to one day in the future device nr0 entered promiscuous mode rtc_cmos 00:00: Alarms can be up to one day in the future rtc_cmos 00:00: Alarms can be up to one day in the future rtc_cmos 00:00: Alarms can be up to one day in the future rtc_cmos 00:00: Alarms can be up to one day in the future audit: type=1400 audit(1574447121.650:108): avc: denied { setattr } for pid=27405 comm="syz-executor.3" name="NETLINK" dev="sockfs" ino=381949 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=netlink_generic_socket permissive=1 rtc_cmos 00:00: Alarms can be up to one day in the future rtc_cmos 00:00: Alarms can be up to one day in the future device nr0 entered promiscuous mode rtc_cmos 00:00: Alarms can be up to one day in the future rtc_cmos 00:00: Alarms can be up to one day in the future rtc_cmos 00:00: Alarms can be up to one day in the future rtc_cmos 00:00: Alarms can be up to one day in the future rtc_cmos 00:00: Alarms can be up to one day in the future rtc_cmos 00:00: Alarms can be up to one day in the future rtc_cmos 00:00: Alarms can be up to one day in the future device nr0 entered promiscuous mode rtc_cmos 00:00: Alarms can be up to one day in the future rtc_cmos 00:00: Alarms can be up to one day in the future rtc_cmos 00:00: Alarms can be up to one day in the future rtc_cmos 00:00: Alarms can be up to one day in the future rtc_cmos 00:00: Alarms can be up to one day in the future rtc_cmos 00:00: Alarms can be up to one day in the future device nr0 entered promiscuous mode rtc_cmos 00:00: Alarms can be up to one day in the future rtc_cmos 00:00: Alarms can be up to one day in the future device nr0 entered promiscuous mode rtc_cmos 00:00: Alarms can be up to one day in the future rtc_cmos 00:00: Alarms can be up to one day in the future device lo entered promiscuous mode device lo left promiscuous mode rtc_cmos 00:00: Alarms can be up to one day in the future device nr0 entered promiscuous mode rtc_cmos 00:00: Alarms can be up to one day in the future rtc_cmos 00:00: Alarms can be up to one day in the future rtc_cmos 00:00: Alarms can be up to one day in the future rtc_cmos 00:00: Alarms can be up to one day in the future device nr0 entered promiscuous mode rtc_cmos 00:00: Alarms can be up to one day in the future device nr0 entered promiscuous mode rtc_cmos 00:00: Alarms can be up to one day in the future rtc_cmos 00:00: Alarms can be up to one day in the future device nr0 entered promiscuous mode rtc_cmos 00:00: Alarms can be up to one day in the future rtc_cmos 00:00: Alarms can be up to one day in the future rtc_cmos 00:00: Alarms can be up to one day in the future device nr0 entered promiscuous mode